The present invention relates to combination ovens used in preparing food, and in particular, to a ventless hood for such an oven, the combination of oven and ventless hood providing rapid access to the oven interior at the conclusion of a cooking schedule.
High-end commercial ovens may provide for closed-system operation in which the oven volume is substantially sealed to retain heat and moisture and provide energy savings. Such closed-system operation is particularly desirable for “combination ovens” that may cook food using steam and fan driven (forced convection) hot air, but is also useful in convection ovens (without steam) and rotisserie ovens.
In closed-system ovens, expanding steam and air are vented so that the cooking process is performed without significant pressurization. This venting may occur through a condenser where the steam is cooled before exiting to the outside air, reducing the heating and humidification of the kitchen environment. In one common condenser design, the steam is passed through a water bath which cools and condenses the steam. The temperature of the water bath is monitored and fresh, cool water is introduced into the water bath as the temperature rises. Excess water from the bath passes through an overflow into the building drain system.
Such closed-system ovens can be used with so-called “ventless fume hoods” which provide internal filters to capture grease and cooking odors when the oven door is opened after a cooking schedule is complete. A common design for such ventless hoods provides an air intake positioned at the front of the oven just above the oven door. When the user attempts to open the oven door, a latch holds the oven door in a partially open position for a short period of time (for example, 20 seconds) to allow the ventless hood to capture and filter the air escaping through the door opening. After this time, the latch is released and the door may be fully opened.
Advanced “multi-mode” closed-system ovens may provide the ability to switch between standard closed operation described above and “open” operation in which the oven is vented during all or portions of the cooking cycle, for example, for humidity control, browning, or the like. This venting operation may be controlled through one or more electrically actuable “dampers” which may open or close to introduce outside air into the oven. A multi-mode oven suitable for this purpose is described in U.S. patent application Ser. No. 13/868,423 filed Apr. 23, 2013, assigned to the assignee of the present invention and hereby incorporated by reference.
When the dampers are open during the cooking cycle, grease and odors from an exhaust damper must be captured even though the oven door is closed and the ventless hood is not operating. The large door intake area needed by the ventless hood prevents a simple routing of the exhaust damper into the ventless hood without the odor and grease simply bypassing the filters and exiting backwards through the door intake area. On the other hand, constant operation of the ventless hood fan at a volume rate sufficient to capture odor or grease simultaneously from the damper and the large door intake area risks drawing so much an through the damper that the accuracy of the cooking process is adversely affected.